This Core will establish, maintain, and provide access to inception cohorts totaling over 1500 rheumatoid arthritis (RA) patients enrolled within their first year of disease and will follow these patients using standard ARAMIS protocols within full Health Assessment Questionnaire (HAQ) administration each six months, for a period of longitudinal follow-up of nine years. These cohorts are (1) large, (2) broadly representative, (3) geographically diverse, (4) encompass alternative management strategies, (5) contain DNA typing data (DRBI *0401 and *0404), and (6) include standardized central laboratory determination of CRP and Rheumatoid Factor, (7) contain frozen cells and serum for future studies, (8) enable search for causative agents in RA through use of newly available protein micro-array technology on stored serum, (9) consist of consecutively seen patients without exclusions, and (10) be maintained for long-term follow-up, including standardized reading of hand radiographs at 4 and 8 years of disease. The Core tasks builds upon investigator and staff skills at physician and patient recruitment and in maintenance of large data sets over the long- term. These inception cohorts will provide a unique and powerful resource in support of Projects 1, 2, 3 and 4 and for national and international collaborations with other investigators.